1. Field of the Invention
This invention relates to a bypass device for influencing blood pressure, including an implant with a volumetric chamber, having connecting means for connecting the volumetric chamber to a natural cardiovascular system, and having an adaptation by which a change in volume of a volume of the volumetric chamber is enabled or effected upon a pressure change in the cardiovascular system or in the volumetric chamber.
2. Discussion of Related Art
German Patent Disclosure DE 10 2004 018 255 Al discloses an implant in the form of a vascular prosthesis, which is embodied essentially as a tube with an elastic inner wall. A nonwoven structure limits the stretchability of the elastic inner wall, so that a flexural strength behavior is attained that is essentially equivalent to the extensibility of natural arteries at both systolic and diastolic pressure. Thus the vascular prosthesis can restore or reinforce the so-called Windkessel effect of the natural arteries and in particular of the aorta. The term “Windkessel function” is understood to mean the retention of some of the blood volume ejected by the heart during systole in the elastic central arteries, and its continuous output during diastole. The Windkessel function makes the arterial blood flow in the peripheral circulatory system more uniform. A reduced or impeded wk function of natural arteries relates to fundamentally more work for the heart, and over the long term, the risk of heart damage rises. With the elastic inner wall of the vascular prosthesis taught by German Patent Disclosure DE 10 2004 018 255 A1, a greater quantity of blood is briefly stored as a result of stretching of the inner wall during systole, the ejection phase of the heart. During diastole, relaxation of the heart muscle, the blood briefly stored in the vascular prosthesis is forced out of the vascular prosthesis again because of the elasticity of the inner wall.
From German Patent Disclosure DE 10 2005 058 409 A1 as well, an implant is known as a replacement for a portion of the aorta or an artery, the volume of the implant being elastically deformable by a spring incorporated into the vessel wall. This implant, too, reinforces the Windkessel effect.
U.S. Pat. No. 6,450,942 B1 discloses an implant for regaining or increasing the resilience of the natural arterial system in order to improve the arterial blood flow. This is intended to reduce the load on the heart muscle, because the heart muscle can perform its work more effectively.
Although by the known devices from the prior art the natural Windkessel effect can be simulated or reinforced, and thus a blood pressure reducing effect is attained, these devices can be employed only to a very limited extent for the treatment of high blood pressure. It appears that continued intake of medications by the patient continues to be necessary. Taking medications can be accompanied by sometimes major or harmful side effects, so that a middle ground is found between the requisite blood pressure regulation and the influence on the welfare of the patient. Also, the success of this form of therapy is largely dependent on the compliance of the patient in taking medications.